What of the White House was not yet complete when

Đáp án D
Giải thích: Clue nằm ở dòn 4 đến 6 của đoạn 1: ”for example, the main staircase was incomplete, which hindered movement from floor to floor, and the future laundry yard was merely a pool of mud, so wet laundry was hung in the unfinished East Room to dry”